Example embodiments of the present invention relate to a liquid crystal display (LCD) apparatus and to a drive circuit which may be included in an LCD apparatus.
LCD devices typically include a pair of confronting transparent substrates which define a narrow gap therebetween, and a liquid crystal layer with dielectric anisotropy contained within the gap. In addition, field-generating electrodes oppose each other on inner surfaces of the respective substrates to define a matrix of pixels therebetween. Voltages applied to the field-generating electrodes produce an electric field in the liquid crystal layer to control optical properties (e.g., transmttance) of the liquid crystal layer. A desired image is displayed on the LCD device by controlling, on a pixel by pixel basis, the voltages applied to the field-generating electrodes.
In an LCD device, scan lines usually refer to lines used to supply gate selection signals, and data lines usually refer to lines used to supply color data (e.g., RGB data). For example, scan lines (gate lines) may extend in a row direction of the pixel matrix, and data lines may extend in a column direction of the pixel matrix. Each pixel of the LCD device includes a switching element such as thin-film transistor (TFT) connected to one of the gate lines and one of the data lines, and a liquid crystal capacitor which is defined by a pixel electrode, a common electrode opposite thereto and the liquid crystal therebetween.
If a continuous unidirectional electric field is applied to each pixel, precipitation of ionic impurities in the liquid crystal layer onto the adjacent electrodes can occur, thereby causing electrochemical reactions in the electrodes. Thus, in order to avoid such deterioration, the polarity of the voltage applied to each pixel may be periodically reversed. For example, if a pixel is driven by positive voltage in one scanning cycle, it may be driven by a negative voltage in a next scanning cycle. This can be done by periodically reversing the opposite polarities of the common electrode voltage and the voltage of the pixel electrode. The polarities may, for example, be reversed (i.e., inverted) on a frame-by-frame basis (frame inversion method (FIM)), on a line-by-line basis (line inversion method (LIM)), or on a pixel-by-pixel inversion basis (dot inversion method (DIM)).